testing a cluster voltage limiter... and some things more before that

[Nacho-RT74]

Hi... I'm checking several stuff to make better testing and calibration procedures on gauges and stuff

first question. With a mechanical stock VL... how to test for 5 volts output ?

I tried 3 diff units and tested with an analog multitester, because obviouslly a digital meter wouldn't meet ever the sampling rate for the mechanic pulses. Two of them where open circuit ( including a new one ) so I had to reattach the ground clip to the wire where it was posible.

One used got me the needle bouncing around 5 volts ( maybe 3 bounces per seconds ). Of course you can notice the 5 volts mark is just right in the middle of the tester needle bounce, so I guess this would mean a nice 5 volts output reading.

the other one was simply damaged!

Time to the NEW ONE with one wire end broken ( nice $20 spent ) close to the ground clip. I had to remove one turn of the wire bound to be able to reattach it to the ground clip. Then testing I got the tester needle bouncing maybe once every second and a half. Needle reached full 12 volts the went back to 0. After maybe a second and a half, once again needle bounces to 12 volts and instantly to 0. NO MATTER WHAT I DID to the adjusting screw, allways got more less the same.

so... opinions on this.

[Nacho-RT74]

Next question and this is about electricty theory which I'm not really good like on practical

when you check for battery voltaje are we testing between 0 and +12volts ? or -6 and +6 volts ? or something similar ?

you will understand the reason of this question later

[Nacho-RT74]

why the previous question ?

to check for gauges calibration!!!

for 5 volts power source it can be used a PC power transformer wich provides 5 volts on one of the ends, but as far I recall these are +5 againts 0 ?

then my next question is, ( and here is the relation with lilwendal AWESOME THREAD )

http://www.dodgecharger.com/forum/index.php?topic=37999.0

OK, WE HAVE 5 VOLTS coming out from VL, but STILL the senders takes the - pole from the battery 12 volts source, which is 12 volts. However lilwandal takes the - lead from same 5 volts power source

Now this is why I asked... batt is 0 againts +12 ? or -6 and +6 ?

As far I recall the DC is produced by electrons jump, what make to change the molecules electrical balance if you remove one electron from one molecule to the other, this makes on side being on - negative side with one electron more, and the next molecule on the + side with one electron less ( protons and neutrons are on center and these doesn't move, just electrons ) so, this is whay I think keep 0 on - side of battery is not posible ? or yes ?

this is where theory kills me.

[Pete in NH]

Hi Nacho,

The battery voltage is 0=Ground against +12 volts.

Measuring the instrument regulator  voltage is not possible with a regular voltmeter as you found out. There is a special type of voltmeter called a dynamic voltmeter that uses the voltage present to heat a  known resistor value and then uses a thermocouple and meter to measure the heat value and is calibrated in voltage. I haven't seen one of these meters in many years but, it would be the type you need to measure the output voltage of the instrument regulator.

A second way to get a rough output voltage value would be to use an oscilloscope to measure the on time and off time of one regulator cycle. The scope would need to be set to a very low sweep speed. The output voltage of the regulator would them be-  input voltage (12v) X on time/total cycle time = output voltage.

The gauge circuits are simple series/loop circuits. One side of the sender unit is connected to ground (0 V) or negative side of the battery. The other side of the sender is connected to one side of the gauge. The other side of the gauge is connected to the regulator output (5V).

Hope this helps.

[Nacho-RT74]

Yeap, I know about the wire loops ends for any thermal kind system

Ok, so I would need an osciloscope... Damn!

However I found ( somehow ) one of the VL reading somehow 5 volts average.

[Dmichels]

Make one of these you can use it to calibrate your gauges then use it instead of the mechanical regulators. I have used one for years now
http://www.moparts.org/Tech/Archive/elec/11.html
Good luck
Dave

[Nacho-RT74]

Yes I know about the transistorized conversion, just was trying somehow how to check for propper voltage output from original units.